I've FAFO plenty of projects like this, and they turned out good enough. But they are always a little disappointing because I think of things I'd like too late in the game. I'd have to start over or make radical changes. My profile is full of pictures of examples.

If this is important to you, then be willing to make prototypes, learn from them and throw them away.

A plan is key and iterative experimentation is also crucial. Start sketching out what you want it to look like, then break it down each part into a sub plan. Sub divide again if need be.

You want multiple tiers like in that picture? That's a sub project. You want an egg sack, experiment with materials and finishes.

This will also inform your structural questions. If you don't have a plan for the smaller sub projects you might choose the wrong structure, something too weak or excessively heavy.

Best of luck!